The use of tufting machines to create tufted articles, for example tufted carpet, is well known. Conventional tufting machines use a reciprocating needle bar carrying a plurality of aligned needles, the needles being constructed and arranged to reciprocably penetrate a backing material passing underneath the needle bar on a bed, including a bed plate section, a bedrail and needle plate. As the needles penetrate the backing material, they carry yarn through the backing which is caught either by a looper to create a looped pile article, or by a hook moving in timed relationship with a knife to create a loop which is then cut to create a cut pile article. It is by these well known processes, for example, that looped pile and tufted cut pile carpeting is made.
Early tufting machines used mechanical devices to reciprocate the needle bar, the loopers, and the looper/knife arrangement of the machine in timed relationship with one another to accomplish this tufting operation. This arrangement included a main drive shaft which was rotated by a drive source, usually a motor. The drive shaft is positioned above the needle bar or bars in the head of the tufting machine, extending from one side to the other, transverse to the direction of backing moving through the machine. As the main drive shaft is rotated, it moves a series of spaced, vertical push rods, which are fastened through connecting elements to the needle bar, toward and away from the bed section and the backing material, as well as moving the looper and/or the hook/knife combination in timed relationship with the reciprocation of the needles. This has been done by using pinions or cams mounted on the main drive shift to reciprocate the push rods, while also using push rods or straps engaged with additional cams positioned on the main drive shaft to operate the looper and/or the looper/knife mechanisms.
Although these tufting machines have proven to be durable and capable of creating a high quality tufted product, an inherent problem has been their reliance upon mechanical connections, i.e. the interlinking of mechanical levers or straps to reciprocate the needle bar, the looper drive, and/or the looper/knife drives. These mechanical connections create a significant amount of mechanical drag, which leads to the creation of heat and increased friction and increased wear and vibration in the drive train. An example of an early tufting machine which uses a mechanical drive system is disclosed in U.S. Pat. No. 3,361,096 to Watkins, as well as in British Patent No. 1,507,201 and British Patent No. 1,304,151.
In the effort to move away from using tufting machines having cams and straps, the use of belt drives for these components was developed. An example of this approach in powering a tufting machine component is the multiple stroke looper mechanism for a stitching machine disclosed in U.S. Pat. No. 4,419,944 to Passons, et al. Passons, et al. passes a drive chain over a sprocket on the drive shaft, with a spaced second sprocket being attached to a cam shaft used to reciprocate a push rod for rocking the loopers in timed relationship with the reciprocation of the needles. A mechanical drive system is still disclosed, which drive system is subject to the inherent problems of mechanical wear, stress, and vibration.
U.S. Pat. Nos. 4,586,445 and 4,665,845 to Card, et al., respectively, disclose a high speed tufting machine using a flexible timing belt to vertically reciprocate the needle bar by transmitting the rotation of the tufting machine drive shaft to a series of aligned sprockets, and including a push rod as a part of a crank mechanism for reciprocating the needle bar. Although these two patents to Card, et al. represented a significant advance in the art by allowing still greater production speeds, Card, et al. did not address the limitation of using the tufting machine main drive shaft for mechanically powering, either directly or indirectly, the driven components in an adjustable timed relationship.
Additional examples of advances in the art are disclosed in U.S. Pat. No. 5,513,586 to Neely, et al., in which a belt driven looper drive assembly is disclosed, as well as in U.S. Pat. No. 5,706,745 to Neely et al., which discloses a belt driven looper and knife drive system.
During the evolution of the tufting machine, the use of laterally shiftable needle bars has also arisen. This is done in order to shift the needles, and thus the yarn carried by these needles with respect to the backing material, to produce carpet with a "graphic" pattern. Another type of tufting machine is disclosed in U.S. Pat. No. 3,026,830 to Bryant et al. which uses a disc-shaped cam, the rotation of which is synchronized with the reciprocation of the needles, and thus the main drive shaft, to shift the needle bar laterally in timed relationship with the reciprocation of the needles.
A tufting machine and tufting method for producing multiple rows of tufts with single lengths of yarn is disclosed in U.S. Pat. No. 4,440,102 to Card, et al. This device uses a cam disc rotated in timed relationship with the rotation of the tufting machine main drive shaft. The cam disc has a pre-determined cam profile, with cam followers riding over the periphery of the cam. The cam followers are operably fastened to a shifting bar which engages the needle bar for transversely shifting the needle bar with respect to the backing material, and the loopers beneath the backing material, for producing tufted articles. Another shiftable needle bar tufting machine is disclosed in U.S. Pat. No. 5,224,434 to Card, et al., which utilized cam rollers riding on opposite sides of the periphery of a pair of spaced cam discs. The cam discs are spaced on opposite sides of a needle bar and used together for transversely shifting the needle bar with respect to the backing material for creating tufted articles in a variety of patterns.
Although these devices utilizing cam discs for transversely shifting the needle bar have proven to be durable and reliable, they are subject to wear. Further, a specific cam profile is needed for each specific pattern required, requiring machine shutdown in order to change over the cam discs to change the pattern of the tufted articles being produced. Moreover, the use of a cam disc system is speed limited by the ability to drive a mechanical system without inducing excess machine vibration and stress.
One approach that sought to minimize the use of mechanical components in shifting needle bars to produce pattern-tufted articles is disclosed in U.S. Pat. No. 4,173,192 to Schmidt, et al. In Schmidt, et al., a hydraulic actuator is used to shift a needle bar transversely with respect to the backing material, the system having an electronic pattern control mechanism controlling the actuator in response to a predetermined stitch pattern. Although the device of Schmidt, et al. relies less upon a mechanical drive train for moving the needle bar transversely, it relies instead upon the use of a hydraulic actuator. This system requires the use of a motor, a hydraulic pump, hydraulic piping, and a hydraulic cylinder, which are subject to wear and which operate under high pressure, thus inducing machine stress, noise, and vibration.
In many tufting applications, the needle bar must be shifted frequently and at high rates of speed, which may result in induced machine stress and component wear. The hydraulic fluid of such a system typically is used to lubricate and cool the system, all of which can allow for hydraulic fluid to be degraded or become contaminated, which may lead to damage of the hydraulic pump, and/or the ported servo-valve controlling the device of Schmidt, et al., thus making the system less reliable. In using a hydraulic cylinder for shifting the needle bar, the problems of hydraulic lag and surge, and/or compression and shock of the hydraulic fluid, occurs, in which precise control of the shifting of the needle bar with respect to the backing material may be adversely affected. Schmidt, et al. also introduced a control system which required the use of a number of external position sensors, as well as a separate pump, motor, cylinder, and/or cylinders, and a servo valve for each cylinder to accomplish the shifting of the needle bar.
The device of Schmidt, et al. was modified in U.S. Pat. No. 4,829,917 to Morgante, et al. Morgante, et al. uses a computer to control the velocity of the transverse movement of the needle bar, accomplished by the hydraulic cylinder, so as to minimize any shock created by the transverse movement of the needle bar. This was achieved by signaling the commencement of the shifting of the needle bar prior to its actual shifting, and by signaling the termination of the shifting prior to the termination of the actual shifting in order to counteract any delayed inertial movement, i.e. fluid shock or compression, in the hydraulic cylinder during the movement of the needle bar in response to the computer command signals. Thus, Morgante, et al. sought to improve the control of the hydraulic actuator.
What has been needed, therefore, but seemingly unavailable in the art is an improved tufting machine having a precision drive system which reduces or moves away from the mechanical interlinkage of the needle bar drive, the shifting of the needle bar, the looper drive, and/or the looper/knife drive systems so that one or more of these components of the tufting machine is powered separately, yet all still work in timed relationship with one another at a high degree of precision.
The known devices are not constructed to perform this task, nor to fulfill these needs, and they fail to suggest how this may reasonably be accomplished. What is provided, therefore, is an improved tufting machine with a precision drive system using a machine controller, typically a computer or computing system, to control either selected or all tufting operations, including the reciprocation of the needle bar, shifting the needle bar, as well as the rocking of the loopers and/or the looper/knives in precise, timed, programmable relationship with one another, yet which eliminates the drive system in which the operation of any one component is mechanically linked to all other components.